1. Field of the Invention
The present invention relates to a disk cartridge accommodating an information recording/reproduction medium (a disk) so that a recording surface of the disk can be protected from contaminants, such as dust or fingerprints, and more particularly, to a disk cartridge in which a disk ascends and descends along protrusion portions formed on a shutter to protect a recording surface of the disk when the shutter is opened and shut.
2. Description of the Related Art
In general, a disk cartridge accommodating a disk, that is, an information recording/reproducing medium, is loaded in a disk drive apparatus. As shown in FIG. 1, a conventional disk cartridge includes a case 101 accommodating a disk D, a shutter 110 installed in the case 101 to be capable of rotating to selectively open/shut a first hole 102 formed on the case 101, so that a pickup (not shown) of the disk drive apparatus can access the disk D, and a cover 103 coupled to an upper portion of the case 101. The disk cartridge includes a second hole 103b formed in the cover 103 to change the disk D, and an escape prevention lever 103a installed on the cover 103 to be capable of sliding so that the disk D does not escape through the second hole 103b. Thus, when the disk D is installed in the disk cartridge, the escape prevention lever 103a is moved back so as not to interfere with the disk D. When the installation of the disk D is completed, the escape prevention lever 103a is moved forward as shown in FIG. 1, so that the disk D is prevented by a leading end portion of the escape prevention lever 103a from escaping through the second hole 103b. 
When the disk cartridge 100 containing the disk D is inserted in the disk drive apparatus as shown in FIG. 2A, an opening lever 120 installed at the disk drive apparatus pushes a locking piece 111a to release a locking state between a protrusion 111c of the shutter 110 and a groove 101a of the case 101. Next, as shown in FIG. 2B, the opening lever 120 pushes and rotates an interference piece 111b. The shutter 110 includes a center hole 114 and first and second shutter portions 111 and 112 which are respectively installed on the case 101 to be capable of rotating around left and right rotation shafts 110a and engaged with each other via an engagement threaded portion 113. When the first shutter portion 111 integrally connected to the interference piece 111b rotates clockwise, the second shutter portion 112 rotates counterclockwise. Accordingly, the first and second shutter portions 111 and 112 are separated from each other to open the first hole 102. Thus, the pickup of the disk drive apparatus can access a recording surface of the disk D through the first hole 102 that is opened, so that information recording and/or reproducing can be performed. Although not shown in FIG. 3, a torsion spring elastically biasing the first shutter portion 111 counterclockwise, that is, in a direction in which the first hole 102 is shut, is installed on the right rotation shaft 110a between the first shutter portion 111 and a bottom surface of the case 101. Thus, when a force applied to the opening lever 120 is removed, the shutter 110 is returned to an original shut state.
However, in the above structure, since the shutter 110 is installed on the case 101, and the disk D is placed on the shutter 110, during an opening/shutting operation of the shutter 110, a surface contact between the recording surface of the disk (the lower surface of the disk in the drawing) and the shutter 110 occurs, so that the recording surface of the disk may be damaged.
Also, dust can enter through the second hole 103b of the cover 103. Of course, since the upper surface of the disk D facing the second hole 103b is not a recording surface, direct contamination by the dust does not occur. However, when the dust is introduced to the disk D through a gap between the disk D and the cover 103 and remains on the shutter 110, the dust on the shutter 110 can adhere to the recording surface of the disk indirectly during the opening/shutting operation.
Therefore, there is a need to protect the recording surface of the disk during the opening/shutting operation of the shutter 110.